Sub sub commands

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Fixes #7
Fixes #12
Fixes #16
Fixes #22
Fixes #27

Example Multi-level autocompletion for --complete: Fixes #7

    [ /sub ] $ sub example advanced fix-7
    bar  foo
    [ /sub ] $ sub example advanced fix-7 foo b
    baz  bla


Nested "sub-sub-commands": Fixes #22

    .
    ├── bin                  # contains the main executable for your program
    ├── completions          # (optional) bash/zsh completions
    ├── libexec              # where the subcommand executables are
    ├───> sub-command-a	     # sub command-a <command> directory
    ├─────> sub-command-b    # sub command-a command-b <command> directory
    └── share 

Example Directory and File Structure: Fixes #22

	.
    ├── bin                  	 # Real Life Example
    ├── completions          	 # Directories return help for children
    ├── libexec            	 # 
	├───> sub-example	       # sub example (Returns help for example)
	├─────> sub-basic    	   # sub example basic (Directory)
	├──────── sub-foreach    	 # sub example basic foreach (Script)
	├──────── sub-files 		 # sub example basic files (Script)
	├────> sub-advanced    	 # sub example advanced (Directory)
	├─────> sub-expert    	   # sub example advanced expert (Directory)
	├──────── sub-case-select  # sub example advanced expert case-select (Script)
	└── share 

Example For Directory Help Helper File: Fixes #22

    ├── libexec             	 # 
    ├───> sub-example	       # sub example (Returns help for example)
    ├───── sub-example         # Provides area for usage, summary, and help
     
Example Help Display With sub-sub-commands: Fixes #22

    [ /sub ] $ sub help
    Usage: sub <command> [<args>]

    Some useful sub commands are:
       commands     List all sub commands
       -> example   Collection of BASH Sub Example Scripts

    See 'sub help <command>' for information on a specific command.

Example Multiple Command w/ Completion: Fixes #22  & Fixes #12

    [ /sub ] $ sub example advanced expert case-select --
    --break  --name

Example Multiple Commands and Flags: Fixes #22

    [ /sub ] $ sub example advanced expert case-select --break 3 --name Jeff
    -=> Executing Case Select Example
    ----> Breaking on 3
    ----> Counter is called Jeff
    ------> The Jeff is 0
    ------> The Jeff is 1
    ------> The Jeff is 2
    - Finished...

Example File Completion:  Fixes #16 & Fixes #27

    [ /sub ] $ sub example basic files
    .git/        .gitmodules  README.md    completions/ plugins/     share/
    .gitignore   LICENSE      bin/         libexec/     prepare.sh